This invention relates to improved apparatus for switching alternating current voltage between an input and an output. Circuits previously used for this purpose dissipate too much power and produce too much radio frequency interference. The simplest switch is a mechanical relay. It produces large amounts of RFI on both opening and closing and has a short life due to the arcing that results, especially when it is opened and the load is inductive. Unidirectional solid state switches have been used, but they create significant amounts of RFI even when on, dissipate a great deal of power and are subject to destruction from current overload and voltage spikes. They may also be turned on after opening by excessive dV/dt when switching inductive loads. In addition, they have moderate off-state leakage current. Whereas bidirectional solid state relays can solve some of these problems, they cannot solve all of them.